Influences of past climatic changes on historical population structure and demography of a cosmopolitan marine predator, the common dolphin (genus D elphinus )

Abstract

Climatic oscillations during the P leistocene have greatly influenced the distribution and connectivity of many organisms, leading to extinctions but also generating biodiversity. While the effects of such changes have been extensively studied in the terrestrial environment, studies focusing on the marine realm are still scarce. Here we used sequence data from one mitochondrial and five nuclear loci to assess the potential influence of Pleistocene climatic changes on the phylogeography and demographic history of a cosmopolitan marine predator, the common dolphin (genus D elphinus ). Population samples representing the three major morphotypes of D elphinus were obtained from 10 oceanic regions. Our results suggest that short‐beaked common dolphins are likely to have originated in the eastern I ndo‐ P acific O cean during the Pleistocene and expanded into the A tlantic O cean through the I ndian O cean. On the other hand, long‐beaked common dolphins appear to have evolved more recently and independently in several oceans. Our results also suggest that short‐beaked common dolphins had recurrent demographic expansions concomitant with changes in sea surface temperature during the P leistocene and its associated increases in resource availability, which differed between the N orth A tlantic and P acific O cean basins. By proposing how past environmental changes had an effect on the demography and speciation of a widely distributed marine mammal, we highlight the impacts that climate change may have on the distribution and abundance of marine predators and its ecological consequences for marine ecosystems.

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